A lifeline represents an individual participant in the interaction.
To create a lifeline, simply double-click anywhere on the diagram canvas. For additional methods, refer to the Diagram Editor page.
From version 9.2 onwards in Astah Professional and Astah UML, lifelines can be created by dragging and dropping a component from the structure tree onto the diagram. This will create a Lifeline with the Component as its base class. This intuitive method simplifies the process of representing your system components as participants in the interaction.
To establish a connection between two lifelines, hover your mouse over a lifeline until the [L] icon appears, then click it to draw a link to another lifeline. This visual link represents the interaction path between the participants.
Messages represent the communication between lifelines.
To create a message, ensure that the two lifelines are already connected with a link.